Regulation of the biopotency of primate luteinizing hormone by gonadotropin-releasing hormone in vitro and in vivo.
Gonadotropin biological/immunological (B/I) ratios have proven to be valuable indicators of the biopotencies of LH and FSH. Observations of rapidly changing LH B/I have been made which suggest the existence of a readily mobilized pool of highly bioactive pituitary gonadotropins. To test this hypothesis, we have examined the role of GnRH in the regulation of LH B/I in vivo and in vitro. The rhesus monkey was used as a model due to its many physiological similarities with the human. A rapid elevation in circulating LH B/I was observed following GnRH administration to male monkeys that was sustained for at least 2 h (15 min; p less than 0.05). The administration of 1 or 10 nM GnRH to cultured pituitary cells was found to significantly increase the B/I of secreted, but not intracellular, LH (p less than 0.05). In unstimulated controls, the B/I of intracellular LH was higher than that of secreted LH (p less than 0.05). These findings are consistent with the notion that a pool of highly active LH exists within the gonadotrophs in primates. One way that GnRH may regulate the bioactivity of circulating LH is by rapidly mobilizing this gonadotropin pool.
Matteri
R L
RL
Wisconsin Regional Primate Research Center, University of Wisconsin, Madison 53715-1299.
Dierschke
D J
DJ
Bridson
W E
WE
Rhutasel
N S
NS
Robinson
J A
JA
D000818:Animals; D001681:Biological Assay; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007120:Immunochemistry; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000276:immunology / Q000378:metabolism*; D008253:Macaca mulatta; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone